Lubricants, such as lubricating oils and greases are subject to oxidative deterioration at elevated temperatures or upon prolonged exposure to the elements. Such deterioration is evidenced, in many instances, by an increase in acidity and viscosity. It can cause metal parts to corrode. Additionally, severe oxidation leads to a loss of lubrication properties which results in the wear of metal parts.
It is known that sliding or rubbing metal or other solid surfaces are subject to wear under conditions of extreme pressure. Wearing is particularly acute in modern engines in which high temperatures and contact pressures are prevalent.
Friction is also a problem any time two surfaces are in sliding or rubbing contact. It is especially significant in an internal combustion engine and power transmission systems, because loss of a substantial amount of the theoretical mileage possible from a gallon of fuel is traceable directly to friction.
Another serious problem in respect to metallic surfaces in contact with adjacent metallic surfaces is the surface wear caused by the contact of such surfaces. The need for improving lubricity via friction modifying additives and prevention of wear by antiwear additives for lubricating oils to meet the ever changing requirements of modern engines is clearly well known. One material capable of simultaneously and effectively coping with these serious problems is highly desirous.
Martischius et al. in U.S. Pat. No. 4,871,375 that issued on Oct. 3, 1989 discloses fuels for Otto engines containing small proportions of an alkali-metal or alkaline-earth metal salts of amic acids where partial amides of tricarboxylic acids such as citric acids are utilized.
Therefore, what is needed is an alkylated carboxylic acid which can be used in the absence of an alkali-metal or alkaline-earth metal salt of amic acids to impart synergistic antiwear and friction modifying properties to lubricants and fuels.